While I was deployed to Fort Clayton in Panama in the early 1990s, I had a MP in my platoon tell us how a military police soldier(rank unknown) had a ND with his issued M9 9mmNATO sidearm. The MP was a National Guard soldier & working in Panama. When he went to turn in his duty pistol to the unit arms room, he fired a FMJ bullet into the arms room clearing barrel. He was so shocked by the loud report, he kept firing round after round! A US Army MP officer yelled out a window for someone to grab the MP & disarm him.
No one was hurt but the MP got UCMJ actions(Uniform Code of Military Justice).

On a another deployment to Panama around the same period, there was a MP Sgt(E-6) who took his loaded M9 pistol off(he had a M12 shoulder holster rig) and left it on a outdoor table by his company bldg. When he returned, the M9 was gone! He got in BIG trouble! That was just stupid.